This invention relates to cement dispersion agents (or cement dispersants). It has been intended with expectations to produce allyletherester monomers as an intermediate product by an esterification reaction of α-allyl-ω-hydroxy-polyoxyalkylene with aliphatic monocarboxylic acid, to obtain vinyl copolymers by a radical copolymerization reaction of such allyletherester monomer with vinyl monomers which are copolymerizable therewith, to obtain grail copolymers by a graft reaction between such vinyl copolymers and polyoxyalkylene monoalkylether, and to use such graft copolymers and their salts as a dispersant, an antistatic agent, an anticlouding agent, an emulsifier or an adherent. In such applications, the quality of the monomers to be used in such radical copolymerization and graft reactions, and in particular the quality of allyletherester monomer, is known to significantly affect the quality of the produced graft copolymers and their salts serving as a dispersant, an antistatic agent, an anticlouding agent, an emulsifier or an adherent. In other words, if the quality of allyletherester monomers obtained as the intermediate product is not sufficiently high, graft copolymers produced therefrom and their salts cannot function satisfactorily as a dispersant, an antistatic agent, an anticlouding agent, an emulsifier or an adherent.
This invention relates to a method for producing allyletherester monomers of high quality without using a solvent and graft copolymers which can be obtained by using such allyletherester monomers of high quality as intermediate product or their salts used as cement dispersant capable of providing a superior fluidity characteristic with a small slump loss to hydraulic cement compositions and high durability in freezing and thawing action and compressive strength to hardened products obtained from such hydraulic cement compositions.
Conventionally, such allyletherester monomers were produced by an esterification reaction between α-allyl-ω-hydroxy-polyoxyalkylene and aliphatic monocarboxylic acid with an organic solvent such as benzene, toluene, cyclohexane and hexane. If such an organic solvent is used for the production, however, the used organic solvent must eventually be collected. This means that the cost of equipment for the collection adds to the total production cost of the allyletherester and hence that of the graft copolymers which are produced by using it as intermediate product. In addition, the workers will be forced to work in an undesirable environment due to some of the properties of these substances.
In particular, what is obtained by a ring-opening addition reaction of alkylene oxide with allyl alcohol is usually used as α-allyl-ω-hydroxy-polyoxyalkylene for the production of allyletherester monomers and such reaction product of ring-opening addition reaction is mass-produced industrially and saved until it is used, that is, until allyletherester monomers are produced by an esterification reaction with aliphatic monocarboxylic acid. If allyletherester monomers are produced by using such α-allyl-ω-hydroxy-polyoxyalkylene, however, it is not possible to produce allyletherester monomers of high quality.